Prior art workers have developed many types of collapsible, portable, article carrying carts for many purposes. Such carts are used, for example, to carry luggage, sample cases, office equipment, electronic equipment, and the like. Examples of collapsible article carrying carts are taught in U.S. Pat. Nos. 3,998,476 and 4,630,837.
Prior art carts of the type to which the present invention is directed are generally characterized by one or more drawbacks. For example, some carts of this type are provided with a single handle element, but have been found to be difficult to manipulate, particularly under heavier loads. Handle assemblies have been devised incorporating a pair of telescoping tube assemblies joined at their upper ends by a grip member. Latch means are provided to lock the telescoping tube assemblies in their extended positions. Such structures are frequently awkward and difficult to unlatch, in order to collapse the handle assembly to its retracted position. The above-mentioned U.S. Pat. No. 3,998,476 teaches an improved release mechanism for a telescoping handle assembly made up of two telescoping tubular assemblies, but a number of manipulative steps are still required to release the handle assembly and shift it to its retracted position.
The main frame portion of many of the prior art carts incorporate sheet steel or cast metal parts for strength, but these parts add considerably to the weight of the cart.
Many of the prior art carts are single purpose carts. Those carts provided with various attachments for greater versatility either require that the attachments be permanent parts of the cart or require tools for their attachment to and removal from the cart. Finally, many prior art cart structures employ elastic cords by which the cart load can be secured in place. Typically, one end of each cord is anchored to a part of the cart. The other end of each cord is provided with a hook member adapted to engage one or more parts of the cart. A problem with this arrangement lies in the fact that should the elastic cord inadvertently become unhooked, or slip from the cart operator's hand during the tie-down procedure, the hooks can be propelled at high speed by the elastic cords to which they are affixed and constitute a danger, which can lead to damage or injury.
The present invention is based upon the discovery that a cart can be made of rod stock, tubing and plastic elements which is very strong, light weight and capable of supporting and transporting loads in the neighborhood of 300 pounds. The cart of the present invention is provided with a telescoping handle assembly made up of a pair of telescoping tubular assemblies joined at their upper ends by a grip member. While the various tubular members are lockable in their extended positions, a greatly simplified unlocking system is provided, making shifting of the handle assembly to its retracted position extremely easy and convenient. The cart of the present invention is provided with an auxiliary rear wheel system which can be applied to the cart without tools and which can easily be collapsed to a stowed position on the cart, or removed from the cart, again without use of tools. The present invention further contemplates other attachments to be described hereinafter, which can be affixed to and removed from the cart with a minimum of simple manipulative steps, and without the use of tools These attachments make the cart a very versatile carrying system. Finally, the cart is provided with elastic security cords. The free ends of the cords are formed into loops which cooperate with cleats on the cart, thereby eliminating the danger of elastic cords terminating in hooks.